Charles Ellicott Commentary Deuteronomy 1:3

"And it came to pass in the fortieth year, in the eleventh month, on the first day of the month, that Moses spake unto the children of Israel, according unto all that Jehovah had given him in commandment unto them;" — Deuteronomy 1:3 (ASV)

And it came to pass in the fortieth year, in the eleventh month. —The “and” is the real beginning of Deuteronomy, and connects it with the previous books. The moral of these words has been well pointed out by Jewish writers. It was only eleven days’ journey from Sinai to Kadesh-barnea—the place from where Israel should have begun the conquest of the promised land; but not only eleven days of the second year of the exodus, but eleven months of the fortieth year found them still in the wilderness. “We see that they could not enter in because of unbelief.”